The early impact of paraquat ban on suicide in Taiwan

Abstract

Introduction: Pesticide ingestion is a leading method for suicide worldwide. Paraquat is a highly lethal herbicide when ingested. We assessed the impact of the first-stage ban on the import and production of paraquat (from February 2018) on suicides by pesticide poisoning in Taiwan.

Methods: Suicide data by method (pesticide vs. non-pesticide), pesticide (paraquat vs. non-paraquat), and area/sex/age were extracted from the national cause-of-death data files (2011-2019). Negative binomial regression was used to estimate changes in suicide rates in 2019, compared to the expected rates based on pre-ban linear trends (2011-2017).

Results: The paraquat ban was followed by an estimated 37% (rate ratio [RR] = 0.63, 95% confidence interval [CI] 0.54-0.74) reduction in pesticide suicide rate (190 [95% CI 116-277] fewer suicides) in 2019, mainly due to a 58% (RR = 0.42, 95% CI 0.33-0.54) reduction in paraquat suicides (145 [95% CI 92-213] fewer suicides). Larger absolute reductions in pesticide suicides were found in rural areas, males, and the elderly (aged 65+ years) than their counterparts. Except for a 10% (95% CI 3-18%) reduction in overall suicide rates in the elderly, there was no statistical evidence for a change in non-pesticide and overall (all-method) suicides.

Conclusion: The ban on the import and production of paraquat was followed by a fall in whole-population pesticide and paraquat suicides and elderly suicides in Taiwan.

Keywords: Pesticide ban; paraquat; pesticide suicide; suicide prevention.